Air filters are often rated using a Minimum Efficiency Reporting Value (MERV) rating; an industry standardized numerical value used to quantify an air filter's filtering ability. The MERV rating allows consumers to compare the ability of different air filters to capture and hold dirt and dust in specific size ranges. Higher MERV ratings mean fewer dust particles and other airborne contaminants pass through the filter.
Air filters for residential use often have relatively low MERV ratings, ranging from about MERV 1 to about MERV 4. Such air filters are generally incapable of removing particles smaller than about 10 microns. Air filters having a MERV rating ranging from about 5 to about 8 are commonly used as high end residential air filters and for commercial applications, and such air filters will collect particles as small as 3 microns. Air filters having a MERV rating ranging from about 9 to about 12 are commonly used in commercial and industrial applications, and will stop particles in the 1 to 3 micron range. The most efficient air filters have MERV ratings of about 13 to about 16, and such air filters will stop particles as small as 0.3 microns. These air filters are used in hospitals and other super clean environments.
Particularly in commercial heating, ventilation, and air conditioning (HVAC) applications, the amount of energy required to move air through all of the air filters in a system can be significant. Even where two air filters have the same MERV rating, those two air filters may require different amounts of energy to force air through each of the two different air filters. The relative air resistance of an air filter can be measured by determining a pressure drop across the air filter. Air filters having relatively lower pressure drops will require less energy to drive air through the air filter.
While many different types of air filters are known, to date there are no air filters available that combine the characteristics of (1) being made entirely from recycled materials; (2) exhibiting a desirable MERV rating; and (3) exhibiting a relatively low pressure drop. It would be desirable to provide such an air filter.